Hallstätter See

A lake of about 8.55 square kilometres and 125 metres deep, named for the town on its western shore, the starting point of the oldest still-working industrial pipeline in the world, which has carried brine to Bad Ischl since 1596 and on to Ebensee. From about 1970 the only ship-mail line in Austria crossed this water; in winters when the western road was blocked by snow or avalanche risk and the ice grew thick enough, mail and passengers went over by sled. The fixed exit weir, a 500-year-old protected monument, flooded houses in Hallstatt in June 2013.